i've done it before, with no issues & used my old sand bed when moving or upgrading my tank. keep in mind those bubbles in the sand bed, like mentioned above, is to be careful on releasing those bubbles which are hydrogen sulfate, not oxygen, from decaying bacteria which are indicated by darker areas in the sand. almost looking like mold, but its a natural process. which releases an acidic gas, that can be harmful to your animals environment & mix into the water column. try syphoning the bubbles out first, then transfer the sand. your live sand bed should already contain great amounts of beneficial bacteria that will help greatly, in establishing your new tank much faster. plus your animals are used to those amounts of beneficial bacteria already. in my experience, the times i depleted those levels when moving & using new sand or rinsing the existing sand, my coral did not respond well. but that has been my experience. happy reefing.